philosophy. Here he died, in B.C. 322, in his sixty-third year. Theophrastus and Eudemus were his immediate successors in the leadership of the school.
Aristotle left behind him an enormous number of writings. Diogenes Laërtius, of uncertain date, gives us a list of 40 works. This probably represents the works bearing Aristotle's name in the Alexandrian Library. A list dating from the time of Cicero makes the total much larger. An ancient tradition says that at the death of Theophrastus, his library, including of course the works of Aristotle, was left to a certain Neleus of Scepsis. His descendants buried the books to save them from the rapacity of the Attalids, who were eager to enrich the Pergamene Library by every possible means. About 100 B.C. the buried collection, naturally much injured by damp and worms, was discovered by Apellicon of Teos, a learned bibliophile, who brought it to Athens. When Sulla captured the city, B.C. 86, he took the books to Rome, where their value was recognized by the grammarian Tyrannion, who had a catalogue prepared by the Peripatetic Andronicus—the longer list mentioned above—and about 40 B.C. published the works thus recovered. Our present recension undoubtedly goes back to this edition, although it is more immediately related to a recension prepared toward the end of antiquity which embraced a number of spurious writings. The later Peripatetics divided the complete works of their master into two classes: exoteric dialogues intended for the public, and acroamatic for the small circle of pupils. To these may be added as a third class certain writings not intended for publication, the hypomnematic works consisting of memoranda and collections on various topics. The exoteric dialogues were well known and much admired in antiquity, but only bare fragments have come down to us. These dialogues did not possess the dramatic character of Plato's works: in place of question and answer, they had long discourses, such as we find in the philosophical writings of Cicero, who chose Aristotle as his model. Among the titles known to us are On the Immortality of the Soul, On Philosophy, On the Good, On Justice, etc. Certain titles, e.g. Menexenus, Gryllus, Nerinthus, The Sophist, etc., remind us of Plato's dialogues. Aristotle carefully prepared these for publication, and must have exhibited in them that perfection of style which caused Cicero to speak of the philosopher's language as a golden stream. The extant works show but little of this quality. These were never completely prepared, and in many eases probably never intended for publication by Aristotle, but were edited by Theophrastus, Eudemus, and the philosopher's son. Nicomachus. Many have the character of lecture notes, possibly those taken by pupils, and most have suffered from interpolations. A considerable number of the works to which his name is now attached are spurious. The extant writings may be classed according to their contents under Logic, Metaphysics, Natural Science, Ethics and Politics, Rhetoric and Poetics.
The works on Logic were called by the later Peripatetics the Organon, "The Instrument," as they deal with the method of investigation. They include the Categories, on the ten classes of predicates—substance, quantity, quality, etc.; On Interpretation, dealing with the proposition and its parts; Analytica Priora, in two books on the syllogism; Analytica Posteriora in two books on the theory of knowledge and the scientific method; Topica in eight books, on dialectics and reasoning from probabilities; and Sophisms on the fallacies of the Sophists and their solution. Aristotle's claim that he was the first to work out a method of reasoning was correct, and formal logic has made little advance since his day; it has only added to his categorical syllogism the hypothetical and disjunctive forms, and has supplemented his three figures by a fourth.
The Metaphysics in thirteen books bears the name given it by later students, because it followed the works on physics in the ancient editions of Aristotle. The philosopher himself called it "First Philosophy" (πρώτ φιλοσοφία). It is in an unsatisfactory condition, consisting of one finished treatise and a number of shorter sketches hardly connected or fully worked out. It begins with a criticism of previous philosophical systems—the earliest history of philosophy — and then, after stating the philosophical questions preliminary to the examination, discusses the doctrine and the ultimate grounds of Being.
The works on Natural Science comprise the Physics in eight books, treating of the general principles and relations of nature; four books On the Heavens, and two on Beginning and Perishing. The last treatise is important for a knowledge of Aristotelian philosophy. The Meteorology discusses the phenomena of the heavens. Natural History is handled in ten books; with it are associated the following treatises: Parts of Animals in four books. Generation in five, and Mode of Progression in one. To these must be added certain works of doubtful authenticity: On Plants in two books, a retranslation from the Latin and probably the work of Nicolaüs of Damascus, who composed, under Augustus, a compendium of Aristotle's philosophy; On the Cosmos, certainly belonging to the Roman period; On the Motion of Animals, On Breathing, On Colors of Plants and Animals, all later than Aristotle. The treatise on Physiognomy, which was composed certainly as late as Hadrian's time, is based apparently on two lost works named in the ancient catalogues of the Aristotelian writings. The Problems, discussions chiefly of physical questions, is also drawn in part from the philosopher's work. The Mechanics, Mirabiles Auscultationes, and some other minor monographs falling within the same field are certainly spurious.
According to Aristotle's own view, psychology was inseparably connected with natural science. Under this head we possess his work On the Soul in three books, and a large number of smaller treatises which are known as the Parva Naturalia.
Next must be named the works on Ethics and Politics, which Aristotle regarded as parts of the same subject. Under the former division there are extant three works: The Nicomachean Ethics in ten books, which takes its name from the philosopher's son, Nicomachus, to whom the work is dedicated and by whom it probably was edited. This is Aristotle's work. The Eudemean Ethics in seven books was prepared by Aristotle's pupil Eudemus on the basis of his master's lectures and the Nicomachean Ethics, with which it coincides in parts. The Magna Moralia in two
